1. Field of the Invention
The present invention relates to a hard disc drive, and more particularly, to a method for determining a type of a head, that is, whether a head is a normal head, a weak head, or an ATE (Adjacent Track Erasure) head, and a method for adjusting a write parameter using the head type determining method.
2. Description of the Related Art
When a conventional hard disc drive prevents a write error depending upon a temperature, it optimizes write parameters such as a write current (WC) and an overshoot control (OSC) based upon temperature. That is, write parameters which are dependent upon temperature are applied to the hard disc drive by predicting a decrease in a write performance of a head depending upon a temperature. For example, Korean Laid-open Patent Publication No. 2002-65356 discloses a technology in which, after a physical characteristic of a storage device, such as a hard disc drive, is estimated in the process of manufacturing the storage device, an optimal parameter is stored in a control device of the storage device. Then, operating parameters of the hard disc drive are dynamically controlled according to a detected environmental condition and the optimal parameter. Further, an apparatus having a temperature sensor, for detecting a temperature in a hard disc drive and varying a write current according to the detected temperature is disclosed in Japanese Laid-open Patent Publication Nos. 1998-340412 and 1994-111457 and Korean Laid-open Patent Publication No. 2002-67794.
Since a coercive force of a disc becomes large at a low temperature, a write parameter is increased, to thereby increase an intensity of a magnetic field. Meanwhile, since a coercive force of a disc becomes small at a high temperature, a write parameter is lowered, to thereby lower an intensity of a magnetic field. Accordingly, a data error can be prevented when data is written.
But since a conventional write parameter optimization method does not consider a specific characteristic of each head in addition to an operating temperature of a hard disc drive, a data error cannot be effectively prevented.
Heads for use in hard disc drives are classified as one of three types: a normal head; an ATE head; and a weak head. The ATE head has a remarkable ATE (Adjacent Track Erasure) effect, and the weak head has a weak write characteristic, that is, a poor write characteristic at a low temperature.
For example, since a coercive force of a disc decreases at a high temperature, an interference between adjacent tracks occurs easily. Thus, in the ATE head, a correction value of a write parameter based upon a temperature needs to be lowered in comparison with the normal head. And since a coercive force of a disc increases at a low temperature, in the weak head, a correction value of a write parameter based upon a temperature needs to be increased in comparison with the normal head.
Since the conventional write parameter optimization method does not consider a specific characteristic of each head, but rather applies the same write parameter correction value to all kinds of heads, problems occur: namely, an interference between adjacent tracks increases in the case of an ATE head at a high temperature, and a weak write phenomenon becomes severe in the case of a weak head at a low temperature.